Add postprocess config file option (useful for applying prettier formatting)

README.md

@@ -158,6 +158,8 @@ There are a few ways to create a config file:
 
 Config files support all the [CLI options](#configuration-options) but in camelCase. CLI options take precedence over config file options.
 
+Using a JavaScript-based config also allows you to provide a `postprocess` function which gets called with the generated content and path to each file as they're processed, to make it easy to apply any custom transformations such as formatting - this is useful if you are using formatting tools such as [`prettier`](#prettier).
+
 Example `.eslint-doc-generatorrc.js`:
 
 ```js
@@ -182,7 +184,22 @@ If you have a build step for your code like [Babel](https://babeljs.io/) or [Typ
 
 ### prettier
 
-If you use [prettier](https://prettier.io/) to format your markdown, you may need to adjust your scripts to run prettier formatting after running this tool:
+If you use [prettier](https://prettier.io/) to format your markdown, you can provide a `postprocess` function to ensure the documentation generated by this tool is formatted correctly:
+
+```javascript
+const prettier = require('prettier');
+const { prettier: prettierRC } = require('./package.json'); // or wherever your prettier config lies
+
+/** @type {import('eslint-doc-generator').GenerateOptions} */
+const config = {
+  postprocess: content =>
+    prettier.format(content, { ...prettierRC, parser: 'markdown' }),
+};
+
+module.exports = config;
+```
+
+Alternatively, you can configure your scripts to run `prettier` after this tool:
 
 ```json
 {

lib/cli.ts

@@ -47,6 +47,7 @@ async function loadConfigFileOptions(): Promise<GenerateOptions> {
       initRuleDocs: { type: 'boolean' },
       pathRuleDoc: { type: 'string' },
       pathRuleList: { anyOf: [{ type: 'string' }, schemaStringArray] },
+      postprocess: {},
       ruleDocNotices: { type: 'string' },
       ruleDocSectionExclude: schemaStringArray,
       ruleDocSectionInclude: schemaStringArray,
@@ -75,6 +76,13 @@ async function loadConfigFileOptions(): Promise<GenerateOptions> {
       );
     }
 
+    if (
+      explorerResults.config.postprocess &&
+      typeof explorerResults.config.postprocess !== 'function'
+    ) {
+      throw new Error('postprocess must be a function');
+    }
+
     return explorerResults.config;
   }
   return {};

lib/generator.ts

@@ -1,5 +1,5 @@
 import { existsSync, mkdirSync, readFileSync, writeFileSync } from 'node:fs';
-import { dirname, join, relative } from 'node:path';
+import { dirname, join, relative, resolve } from 'node:path';
 import { getAllNamedOptions, hasOptions } from './rule-options.js';
 import {
   loadPlugin,
@@ -140,6 +140,8 @@ export async function generate(path: string, options?: GenerateOptions) {
     options?.urlConfigs ?? OPTION_DEFAULTS[OPTION_TYPE.URL_CONFIGS];
   const urlRuleDoc =
     options?.urlRuleDoc ?? OPTION_DEFAULTS[OPTION_TYPE.URL_RULE_DOC];
+  const postprocess =
+    options?.postprocess ?? OPTION_DEFAULTS[OPTION_TYPE.POSTPROCESS];
 
   // Gather details about rules.
   const details: RuleDetails[] = Object.entries(plugin.rules)
@@ -211,10 +213,9 @@ export async function generate(path: string, options?: GenerateOptions) {
     );
 
     const contents = readFileSync(pathToDoc).toString();
-    const contentsNew = replaceOrCreateHeader(
-      contents,
-      newHeaderLines,
-      END_RULE_HEADER_MARKER
+    const contentsNew = await postprocess(
+      replaceOrCreateHeader(contents, newHeaderLines, END_RULE_HEADER_MARKER),
+      resolve(pathToDoc)
     );
 
     if (check) {
@@ -277,21 +278,24 @@ export async function generate(path: string, options?: GenerateOptions) {
 
     // Update the rules list in this file.
     const fileContents = readFileSync(pathToFile, 'utf8');
-    const fileContentsNew = updateRulesList(
-      details,
-      fileContents,
-      plugin,
-      configsToRules,
-      pluginPrefix,
-      pathRuleDoc,
-      pathToFile,
-      path,
-      configEmojis,
-      ignoreConfig,
-      ruleListColumns,
-      urlConfigs,
-      urlRuleDoc,
-      splitBy
+    const fileContentsNew = await postprocess(
+      updateRulesList(
+        details,
+        fileContents,
+        plugin,
+        configsToRules,
+        pluginPrefix,
+        pathRuleDoc,
+        pathToFile,
+        path,
+        configEmojis,
+        ignoreConfig,
+        ruleListColumns,
+        urlConfigs,
+        urlRuleDoc,
+        splitBy
+      ),
+      resolve(pathToFile)
     );
 
     if (check) {

lib/options.ts

@@ -66,4 +66,5 @@ export const OPTION_DEFAULTS = {
   [OPTION_TYPE.SPLIT_BY]: undefined,
   [OPTION_TYPE.URL_CONFIGS]: undefined,
   [OPTION_TYPE.URL_RULE_DOC]: undefined,
+  [OPTION_TYPE.POSTPROCESS]: (content: string) => content,
 } satisfies Record<OPTION_TYPE, unknown>; // Satisfies is used to ensure all options are included, but without losing type information.

lib/types.ts

@@ -100,6 +100,7 @@ export enum OPTION_TYPE {
   SPLIT_BY = 'splitBy',
   URL_CONFIGS = 'urlConfigs',
   URL_RULE_DOC = 'urlRuleDoc',
+  POSTPROCESS = 'postprocess',
 }
 
 /** The type for the config file and internal generate() function. */
@@ -111,6 +112,10 @@ export type GenerateOptions = {
   initRuleDocs?: boolean;
   pathRuleDoc?: string;
   pathRuleList?: string | string[];
+  postprocess?: (
+    content: string,
+    pathToFile: string
+  ) => string | Promise<string>;
   ruleDocNotices?: string;
   ruleDocSectionExclude?: string[];
   ruleDocSectionInclude?: string[];

test/lib/cli-test.ts

@@ -14,6 +14,7 @@ const configFileOptionsAll: { [key in OPTION_TYPE]: unknown } = {
   initRuleDocs: true,
   pathRuleDoc: 'www.example.com/rule-doc-from-config-file',
   pathRuleList: 'www.example.com/rule-list-from-config-file',
+  postprocess: (content: string) => content,
   ruleDocNotices: 'type',
   ruleDocSectionExclude: [
     'excludedSectionFromConfigFile1',
@@ -93,6 +94,7 @@ const cliOptionsAll: { [key in OPTION_TYPE]: string[] } = {
     '--url-rule-doc',
     'https://example.com/rule-doc-url-from-cli',
   ],
+  [OPTION_TYPE.POSTPROCESS]: [],
 };
 
 describe('cli', function () {
@@ -316,7 +318,11 @@ describe('cli', function () {
   });
 
   describe('invalid config file', function () {
-    beforeEach(function () {
+    afterEach(function () {
+      mockFs.restore();
+    });
+
+    it('throws an error', async function () {
       mockFs({
         'package.json': JSON.stringify({
           name: 'eslint-plugin-test',
@@ -325,15 +331,39 @@ describe('cli', function () {
           version: '1.0.0',
         }),
 
-        '.eslint-doc-generatorrc.json': '{ "unknown": true }', // Doesn't match schema.
+        '.eslint-doc-generatorrc.json': JSON.stringify({
+          // Doesn't match schema.
+          unknown: true,
+        }),
       });
-    });
 
-    afterEach(function () {
-      mockFs.restore();
+      const stub = sinon.stub().resolves();
+      await expect(
+        run(
+          [
+            'node', // Path to node.
+            'eslint-doc-generator.js', // Path to this binary.
+          ],
+          stub
+        )
+      ).rejects.toThrow('config file must NOT have additional properties');
     });
 
-    it('throws an error', async function () {
+    it('requires that postprocess be a function', async function () {
+      mockFs({
+        'package.json': JSON.stringify({
+          name: 'eslint-plugin-test',
+          main: 'index.js',
+          type: 'module',
+          version: '1.0.0',
+        }),
+
+        '.eslint-doc-generatorrc.json': JSON.stringify({
+          // Doesn't match schema.
+          postprocess: './my-file.js',
+        }),
+      });
+
       const stub = sinon.stub().resolves();
       await expect(
         run(
@@ -343,7 +373,7 @@ describe('cli', function () {
           ],
           stub
         )
-      ).rejects.toThrow('config file must NOT have additional properties');
+      ).rejects.toThrow('postprocess must be a function');
     });
   });
 });

test/lib/generate/__snapshots__/option-postprocess-test.ts.snap

@@ -0,0 +1,24 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`generate (postprocess option) basic calls the postprocessor 1`] = `
+"## Rules
+<!-- begin auto-generated rules list -->
+
+| Name                           |
+| :----------------------------- |
+| [no-foo](docs/rules/no-foo.md) |
+
+<!-- end auto-generated rules list -->
+
+
+Located at README.md"
+`;
+
+exports[`generate (postprocess option) basic calls the postprocessor 2`] = `
+"# test/no-foo
+
+<!-- end auto-generated rule header -->
+
+
+Located at docs/rules/no-foo.md"
+`;

test/lib/generate/option-postprocess-test.ts

@@ -0,0 +1,59 @@
+import { generate } from '../../../lib/generator.js';
+import mockFs from 'mock-fs';
+import { dirname, resolve, relative } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { readFileSync } from 'node:fs';
+import { jest } from '@jest/globals';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+
+const PATH_NODE_MODULES = resolve(__dirname, '..', '..', '..', 'node_modules');
+
+describe('generate (postprocess option)', function () {
+  describe('basic', function () {
+    beforeEach(function () {
+      mockFs({
+        'package.json': JSON.stringify({
+          name: 'eslint-plugin-test',
+          exports: 'index.js',
+          type: 'module',
+        }),
+
+        'index.js': `
+              export default {
+                rules: {
+                  'no-foo': {
+                    meta: {},
+                    create(context) {}
+                  },
+                },
+              };`,
+
+        'README.md': '## Rules\n',
+
+        'docs/rules/no-foo.md': '',
+
+        // Needed for some of the test infrastructure to work.
+        node_modules: mockFs.load(PATH_NODE_MODULES),
+      });
+    });
+
+    afterEach(function () {
+      mockFs.restore();
+      jest.resetModules();
+    });
+
+    it('calls the postprocessor', async function () {
+      await generate('.', {
+        postprocess: (content, path) =>
+          [
+            content,
+            '',
+            `Located at ${relative('.', path).replace(/\\/gu, '/')}`, // Always use forward slashes in the path so the snapshot is right even when testing on Windows.
+          ].join('\n'),
+      });
+      expect(readFileSync('README.md', 'utf8')).toMatchSnapshot();
+      expect(readFileSync('docs/rules/no-foo.md', 'utf8')).toMatchSnapshot();
+    });
+  });
+});